Seal for coaxial cable in downhole tools

Abstract

A seal for a coaxial cable electrical connector more specifically an internal seal for a coaxial cable connector placed within a coaxial cable and its constituent components. A coaxial cable connector is in electrical communcation with an inductive transformer and a coaxial cable. The connector is in electrical communication with the outer housing of the inductive transformer. A generally coaxial center conductor, a portion of which could be the coil in the inductive transformer, passes through the connector, is electrically insulated from the connector, and is in electrical communication with the conductive core of the coaxial cable. The electrically insulating material also doubles as a seal to safegaurd against penetration of fluid, thus protecting against shorting out of the electrical connection. The seal is a multi-component seal, which is pre-compressed to a desired pressure rating. The coaxial cable and inductive transformer are disposed within downhole tools to transmit electrical signals between downhole tools within a drill string. The internal coaxial cable connector and its attendant seal can be used in a plurality of downhole tools, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

1. A seal for a coaxial cable connector:
 the coaxial cable connector comprising a tube with an upset portion at an end of the tube and a generally coaxial center conductor, the coaxial center conductor passing through the tube and the seal; 
 the seal contained within the upset portion of the tube, the seal comprising: 
 a first bead disposed within the upset portion; 
 a compliant tube having one end adjacent to the bead; 
 a second, packing bead adjacent to the other end of the compliant tube; 
 an annular loading body adapted to engage the upset portion and adjacent the second packing bead; 
 wherein, upon insertion, the annular loading body compressing the second packing bead and the compliant tube between the loading body and the first bead such that the compliant tube plastically deforms and seals against the upset portion and the coaxial center conductor wherein the first bead has a tapered rounded edge to mate with a contour of the upset portion bottom. 
 
     
     
       2. The seal for a coaxial cable connector of  claim 1 , wherein the seal is pre-compressed to 25,000 psi. 
     
     
       3. The seal for a coaxial cable connector of  claim 1  wherein the bead is constructed of ceramic. 
     
     
       4. The seal for a coaxial cable connector of  claim 3  wherein the ceramic is selected from the group consisting of cemented tungsten carbide, alumina, silicon carbide, silicone nitride, and polycrystalline diamond. 
     
     
       5. The seal for a coaxial cable connector of  claim 1  wherein the bead is constructed of metal. 
     
     
       6. The seal for a coaxial cable connector of  claim 5  wherein the metal is selected from the group consisting of steel, titanium, chrome, nickel, aluminum, iron, copper, tin, and lead. 
     
     
       7. The seal for a coaxial cable connector of  claim 6  wherein the steel is selected from the group consisting of viscount 44, D2, stainless steel, tool steel, and 4100 series steels. 
     
     
       8. The seal for a coaxial cable connector of  claim 1  wherein the bead is constructed of a rigid plastic material. 
     
     
       9. The seal for a coaxial cable connector of  claim 8  wherein the plastic material is selected from the group consisting of polyether ether ketones and polyether ketone ketones. 
     
     
       10. The seal for a coaxial cable connector of  claim 1  wherein the compliant tube is made of Teflon. 
     
     
       11. The seal for a coaxial cable connector of  claim 1  wherein an internal diameter of the compliant tube is smaller than an outer diameter of the coaxial center conductor. 
     
     
       12. The seal for a coaxial cable connector of  claim 1  wherein the packing bead has a truncated tapered edge. 
     
     
       13. The seal for a coaxial cable connector of  claim 1  wherein the packing bead is constructed of pyrophyllite. 
     
     
       14. The seal for a coaxial cable connector of  claim 1  wherein the packing bead is constructed of polyether ether ketone and polyether ketone ketone. 
     
     
       15. The seal for a coaxial cable connector of  claim 1  wherein the annular loading body has external circumferential barbs. 
     
     
       16. The seal for a coaxial cable connector of  claim 1  wherein the annular loading body is constructed of is metal. 
     
     
       17. The seal for a coaxial cable connector of  claim 15  wherein the metal is selected from the group consisting of steel, titanium, chrome, nickel, aluminum, iron, copper, tin, and lead. 
     
     
       18. The seal for a coaxial cable connector of  claim 16  wherein the steel is selected from the group consisting of viscount 44, D2, stainless steel, tool steel, and 4100 series steels.